Although improvements have been reported by using cross-domain, cross-task, and cross-lingual transfers, a big challenge in these approaches is finding related source task, domain, and language. In other words, the knowledge learned in solving a source task in a source domain and language can be transferred, only if the knowledge is indeed shared between the source and target. In this thesis, we focus on English datasets; therefore, we do not discuss cross-lingual in details; we refer readers to  [1]}, [2]}, [3]} for more discussions.
